The present invention relates to valves. In particular, the present invention relates to valves to seal an access that can also accommodate a device there through.
In the last several years, minimally invasive surgical procedures have become increasingly common. Laparascopic procedures, treatment of vasculature, and other similar procedures can be done in a minimally invasive manner. For example, an Abdominal Aortic Aneurysm (AAA) may require placement of an aortic graft at the site of the aneurysm. The graft is deployed at the site of the aneurysm by a catheter.
The AAA graft procedure referred to above involves the advancement of the catheter to the site of the aneurysm. Access by the catheter to the aneurysm can be provided through an introducer sheath placed within the Superficial Femoral Artery (SFA). The introducer sheath accommodates a host of instruments during its placement and subsequent placement of the aortic graft as described further herein. The introducer sheath includes an access tube with an internal diameter large enough to accommodate the largest instrument used during the endovascular AAA procedure, with respect to outer diameter.
Generally an introducer sheath is placed within the SFA of a patient with a portion extending into the SFA from outside the body of the patient. To place the introducer sheath in this manner, a puncture is made into the SFA with a needle. The needle is replaced by a guidewire. The guidewire provides initial access to the SFA. Subsequently, a dilator of larger outer diameter than the guidewire is used. The dilator, with the introducer sheath coaxially thereabout, is threaded over the guidewire and into the SFA. The dilator is of an outer diameter such that the introducer sheath can fit snugly around the dilator. The guidewire and the dilator can be removed leaving the introducer sheath in place to provide a means of access to the SFA which leads to the vessel to be treated.
A subsequent guidewire can be inserted into the SFA through the introducer sheath. The catheter can be inserted over the guidewire and through the introducer sheath and advanced to the aneurysm site to be treated. The AAA graft can then be deployed at the site of the aneurysm.
In the procedure described above, the introducer sheath and dilator are initially inserted. The introducer sheath then accommodates no instrument at all as the dilator and initial guidewire are removed, then accommodates another guidwire, and lastly accommodates the catheter. With respect to outer diameters of all of the instruments, there is a general increase in size from no instrument, to guidewire, to dilator and catheter size, which are of the same general size. That is, the introducer sheath accommodates a diameter range of zero (i.e. no instrument) to the size of the catheter and dilator (i.e. which can be up to about 8.28 mm) and also accommodates instrument sizes in between. For example, 0.53 mm guidewires can be used. In the given scenario the introducer sheath must include an opening to provide instrument access. Furthermore, the introducer sheath must accommodate instruments that range from 0.53 mm to 8.28 mm in diameter. This is an increase of about 1,656% from the size of the guidewire to the size of the catheter and dilator.
During the procedure described above, blood in the SFA is of a pressure higher than the pressure found outside of the body. As a result the introducer sheath is susceptible to leakage. Therefore, a valve is generally placed at the proximal portion of the introducer sheath in an attempt to control hemostasis and avoid leakage. However, as noted above, the valve includes an opening to accept instruments that can be as large as, for example, 8.28 mm in diameter, and thus, the introducer sheath remains susceptible to leakage when no instrument is present through the valve. Furthermore, a typical valve is not able to accommodate a range of instrument sizes greater than about 700% from one instrument size to the next while still controlling hemostasis. This is because typical valve material will tend to tear if expanded beyond this point.
As an alternative the valve can be composed entirely of a stronger, foam-like, material, for example. However, where this is the case, the valve will provide too much friction for instruments to easily or smoothly pass through the valve. For example, deformable instruments, such as the 8.28 mm catheter referenced above, will tend to kink or buckle during passage through the valve.
Therefore, what is desired is a valve assembly to accommodate an instrument and avoid leakage when no instrument is present. A valve assembly is also desired to easily or smoothly accommodate a wide range of instrument diameters while preventing leakage.
An embodiment of the present invention provides a valve assembly with a first valve member having a first passageway. A second valve member is provided with a second passageway. A first portion of the first passageway and a second portion of the second passageway are non-overlapping. A compression member is provided adjacent the first valve member.
In another embodiment of the invention a medical access device is provided having an access portion for positioning in a body portion of a patient. A valve assembly coupled to the access portion has first and second valve members having passageways at least partially non-overlapping. A compression member is included adjacent the first valve member.
In a method of the invention a first valve member with a first passageway is provided. A second valve member with a second passageway is placed adjacent the first valve member. A compression member is coupled to a position adjacent the first valve member.